Intranet Project - Rad Or Waterfall?

Discussion in 'Python' started by bs866806@163.com, Jan 8, 2008.

  1. Guest

    I have often used the analogy of building a bridge to explain to
    business colleagues the difference between Rapid Application
    Development (RAD) and Waterfall.

    Let's say that we are in the middle ages and the Mayor of Kingston-
    upon-Thames is evaluating whether or not to build a bridge over the
    river to the north side, to replace the current ferry. The whole area
    has been growing rapidly and a bridge at Kingston should give his town
    a lead against competing local towns like Ham and Richmond (who also
    have their own ferries).

    However, building a bridge presents problems. Firstly, the bedrock
    north and south of the river are very different. Secondly, the river
    is still tidal at this point and its path continues to vary across the
    floodplain. Finally - and perhaps most importantly - there is no
    guarantee that the projected growth in cross-river traffic will indeed
    materialise - or that people will wish to cross at this precise point,
    rather than further up, or down, river. A new bridge could prove an
    expensive white elephant and divert much-needed town resources away
    from other projects. The increased local taxes required could also
    scare the very businesses he is hoping to attract away to other local
    towns.

    Option 1 - Waterfall

    Waterfall, as a methodology, is all about building reliable systems.
    At each stage of the lifecycle, the results are correct. The Mayor's
    engineer believes that - when building a bridge - the result needs to
    be safe, sound and capable of lasting for decades. He recommends a
    design phase, which includes thoroughly testing the bedrock by driving
    piles and developing ways to limit the future variance of the river's
    course. During the build phase, the bridge would be tested to ensure
    it can take the loads that will be placed upon it and to deal with
    high winds or flood conditions. The engineer confirms that each stage
    would only start once the previous stage had been proved correct
    beyond reasonable doubt. The stone bridge will take five whole years
    to build (with a high upfront cost commitment). If the project were
    ever stopped, the value tied up in phases to date would be lost. The
    engineer reminds the Mayor that a collapsed bridge would not help his
    place in history!

    Option 2 - RAD

    RAD, as a methodology is all about building relevant systems. The
    argument runs that it is better to be there quickly with 80% of the
    functionality in 20% of the time, so as to take full advantage of the
    business opportunity. The Mayor's political advisors recommend the RAD
    option; to lay a pontoon bridge first alongside the existing ferry.
    This can be achieved in just three months, using a series of boats
    with a makeshift road surface and swing bridge lock for river vessels
    to navigate. The pontoon bridge allows the business model to be tested
    very quickly; If the expected benefits materialise, then further
    iterations of the bridge can be constructed later on. Sounds good, but
    of course (overall) the costs will be higher than waterfall if a full,
    stone bridge is ultimately required. In the meantime, if the river
    changes course, or floods impact the area, then the pontoon bridge
    will be washed away. His chief advisor reminds him that a bridge five
    years from now would not help his re-election prospects two years
    hence!

    The Mayor's selected option

    Hmm. Interesting, isn't it. Not a clear-cut decision. There are good
    arguments for either approach. The Mayor's decision will ultimately
    depend on (a) how sure he is of his own vision, (b) his financial and
    time constraints and (c) how changeable these factors are likely to be
    over time. In short, he has a trade-off decision of relevance vs.
    reliability.

    Turning the analogy onto Intranet Projects

    In chapter 16 of my Intranet Portal Guide, I explore these concepts in
    a bit more depth.However - put simply - the answer for you will depend
    largely on how sure you are of your vision, the support of
    stakeholders, the availability of resources and the degree of change
    in your organisation and it's requirements.

    If you are operating in a stable business environment and are well
    funded and supported, then waterfall offers real benefits. You could
    establish an Intranet Portal that is well founded, scalable and
    secure. If not, then RAD could offer you the means to make some
    progress now at low cost and use the results of your early work to
    build a stronger case for future investment. It also allows you to
    vary the approach - or begin again - should circumstances or
    requirements change.

    Most Intranet evangelists will find themselves perhaps in a mixed
    situation, where there is support and funding but there is also the
    risk of rapid changes to the underlying business environment and
    requirements. Here, I would recommend a mixed approach: Use a
    waterfall project to establish the underlying portal infrastructure
    (as this platform will be the bedrock on which you will build and
    needs to stand the test of time). Then use a RAD method to build the
    content and applications (developing solutions that are timely and
    relevant to businesses operating in a fast-moving and competitive
    environment).
    http://cncarrental.cn/html/Internet/20060929/31828.html
     
    , Jan 8, 2008
    #1
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  2. GHUM Guest

    Re: Intranet Project - Rad Or Waterfall

    > Option 1 - Waterfall

    I recommend to google "waterfall". First hit after those beatifull
    pictures will be:

    http://en.wikipedia.org/wiki/Waterfall_model

    Within the first paragraph there is:

    """Ironically, Royce was actually presenting this model as an
    example of a flawed, non-working model.(Royce 1970)"""


    So I cannot fight the feeling of seeing the realisation of a xkcd-
    strip when reading about waterfall models...

    Harald
     
    GHUM, Jan 8, 2008
    #2
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